Email Reply Builder

Reply to emails from your own custom domain and keep the full conversation history intact. Paste the original email, write your reply, and send it through Resend — the history is preserved automatically.

The original email is parsed in your browser. Your Resend API key is used only for this send request and is not stored or logged.

Build a reply

Raw email

Copy from Gmail Show original or Outlook View Source.

Parsed context

Paste raw email to see thread headers and sender mapping.

Your reply

Quote mode

Send with Resend

Reply subject *

Enter the reply subject.

Reply target *

Enter the email address to reply to.

Resend API key *

Used only for this send request. Not stored or logged.

Sender email *

Use a sender address from a verified Resend domain

Sender name

Attachments

Optional. Total attachments up to 9.0 MB.

How to use

Open the email you want to reply to and copy its full source. In Gmail, click the three-dot menu and choose "Show original"; in Outlook, use "View Source".
Paste the source into the tool. The sender, subject, and conversation context are extracted automatically.
Write your reply. Choose whether to include the quoted original message.
Enter your Resend API key and sender address (must be from your verified domain), then send.

Use cases

Reply from a custom domain (like [email protected]) to emails received via Cloudflare Email Routing.
Keep replies inside the original Gmail or Outlook conversation thread so the recipient sees full context.
Handle business email without setting up a full email client or mail server.
Quickly reply to forwarded or routed emails while keeping a clean sender identity.

Privacy and data handling

Raw email parsing happens in the browser.
The send request sends your temporary Resend key and final email payload through the Easton Tools API proxy.
API keys, raw email, reply content, email addresses, and attachments are not stored or logged by the tool.
Resend receives the final message payload in order to send the email.

FAQ

Will the reply always stay in the same thread?

Threading depends on the receiving email client, but adding correct In-Reply-To and References headers gives Gmail and similar clients the context they need.

Do you store my Resend API key?

No. The key is kept in browser state and sent only with the current API request to Resend through the proxy.

Can I send attachments?

Yes. Files are read locally, converted to Base64 for Resend, and limited before sending.